From: Yun Zhou <yun.zhou@windriver.com>
To: <rostedt@goodmis.org>
Cc: <linux-kernel@vger.kernel.org>,
<kernel-hardening@lists.openwall.com>, <ying.xue@windriver.com>,
<zhiquan.li@windriver.com>
Subject: [PATCH 1/2] seq_buf: fix overflow in seq_buf_putmem_hex()
Date: Sat, 26 Jun 2021 11:21:55 +0800 [thread overview]
Message-ID: <20210626032156.47889-1-yun.zhou@windriver.com> (raw)
There's two variables being increased in that loop (i and j), and i
follows the raw data, and j follows what is being written into the buffer.
We should compare 'i' to MAX_MEMHEX_BYTES or compare 'j' to HEX_CHARS.
Otherwise, if 'j' goes bigger than HEX_CHARS, it will overflow the
destination buffer.
This bug exists in the original code (commit 5e3ca0ec76fce 'ftrace:
introduce the "hex" output method'). Although its original design did
not support more than 8 bytes, the only check on length seems to have
mistaken the comparison object, 'len' should compare to 'HEX_CHARS/2'.
BUG_ON(len >= HEX_CHARS);
Signed-off-by: Yun Zhou <yun.zhou@windriver.com>
---
lib/seq_buf.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/lib/seq_buf.c b/lib/seq_buf.c
index 6aabb609dd87..223fbc3bb958 100644
--- a/lib/seq_buf.c
+++ b/lib/seq_buf.c
@@ -228,8 +228,10 @@ int seq_buf_putmem_hex(struct seq_buf *s, const void *mem,
WARN_ON(s->size == 0);
+ BUILD_BUG_ON(MAX_MEMHEX_BYTES * 2 >= HEX_CHARS);
+
while (len) {
- start_len = min(len, HEX_CHARS - 1);
+ start_len = min(len, MAX_MEMHEX_BYTES);
#ifdef __BIG_ENDIAN
for (i = 0, j = 0; i < start_len; i++) {
#else
--
2.26.1
next reply other threads:[~2021-06-26 3:32 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-26 3:21 Yun Zhou [this message]
2021-06-26 3:21 ` [PATCH 2/2] seq_buf: Make trace_seq_putmem_hex() support data longer than 8 Yun Zhou
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210626032156.47889-1-yun.zhou@windriver.com \
--to=yun.zhou@windriver.com \
--cc=kernel-hardening@lists.openwall.com \
--cc=linux-kernel@vger.kernel.org \
--cc=rostedt@goodmis.org \
--cc=ying.xue@windriver.com \
--cc=zhiquan.li@windriver.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).